Seismic Base Isolation Device for Protection of Equipment Using Roller Ball Transfer Bearings and a Reversion System Comprised of Tension Springs or Viscous Dampers

ABSTRACT

The present invention generally relates to the making of a base isolation device to be used for the protection of non-structural items and equipment. There is known a base isolation device for the protection of non-structural equipment in which the device incorporates the use of caster wheels in conjunction with a proprietary universal spring to revert the isolation device to its original position. However, because such a device is supported on caster wheels, it has a minimum height above 3 inches. Many sensitive electronic equipment which need be ordinarily operated by people sitting behind desks and tables (such as desk top computers in emergency centers and sensitive hospital equipment in surgery rooms) may not allow a height increase of over 3 inches. Additionally, such a device incorporates a proprietary universal spring which can only be specified, designed, and provided by the inventor.This invented base isolation device has a height of less than 3 inches and does not use any proprietary springs but uses non-proprietary springs which are readily available for sale and less expensive than any proprietary counterparts. The present invention discloses an isolation device comprising a base plate, an isolation plate with four legs, and roller balls in each leg sitting on the base plate, four internal springs, two external springs.When the base plate, which is attached to ground, moves with the ground earthquake shakings, the isolation plate, supported by the roller ball transfer bearings, rolls over the base plate and prevents the transfer of forces to the overlying equipment. Once the ground shaking ends, the springs pull back the isolation plate to its original position, laterally and rotationally. The height of the isolation device could be as low as 3 inches.

TECHNICAL FIELD

The present invention generally relates to protection of non-structural equipment from earthquake damage.

BACKGROUND ART

There is known a base isolation device for the protection of non-structural equipment in which the device incorporates the use of caster wheels in conjunction with a proprietary universal spring to revert the isolation device to its original position. However, because such a device is supported on caster wheels, it has a minimum height of 7″, which may not be feasible or aesthetically appealing for use. Additionally, to revert to its original position such a device incorporates proprietary universal springs which are not readily available in the open market, and must be specified, designed, priced, and provided only by the inventor of the known base isolation device.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates the Top View of the preferred embodiment of an isolation device according to the present invention;

FIG. 2 illustrates the Front View of the preferred embodiment of an isolation device according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

All numbered parts are depicted in the submitted drawings.

An isolation device is, provided with a Base Plate (1) located at the bottom which will be attached to the supporting ground. A Center Steel Hook (2) is affixed to the center of the base plate. Attach two Steel Rings (3) to the Center Steel Hook (2). An Isolation Plate (5) is supported by four Hollow Cylindrical Legs (6) attached to the bottom of the Isolation Plate (5). Each Hollow Cylindrical Leg (6) has a Steel Hook (7) installed on the perimeter of the Hollow Cylindrical Leg (6) and along lines connecting the center of the Hollow Cylindrical Leg (6) to the Center Steel Hook (2) and located in between the Hollow Cylindrical Leg (6) and the Center Steel Hook (2). Four Tension Springs (4) are attached to the two Steel Rings (3). The other ends of the two Tension Springs (4) are attached to the four Steel Hooks (7). Each Hollow Cylindrical Leg (6) contains a Roller Ball Transfer Bearing (8). Two Steel Hooks (9) are installed to the corners of the Isolation Plate (5). Two Steel Hooks (10) are affixed to the corners of the Base Plate (1). A minimum of two Tension Springs or Viscous Dampers (11) connect the two Steel Hooks (9) on the Isolation Plate (5) to the Steel Hooks (11) on the Base Plate (1). 

1. Characterized in that the said Base plate (1) is affixed to ground and moves with ground earthquake movements.
 2. Characterized in that The Isolation Plate (5) supported by Roller Ball Transfer Bearings (8) rolls over the said Base Plate (1), therefore isolates the transfer of ground earthquake forces into the supporting equipment.
 3. Characterized in that during the ground earthquake shakings, the internal Tension Springs or Viscous Dampers (4) and external Tension Springs or Viscous Dampers (11) which all exhibit low stiffnesses expand and allow very little load to be transferred from the Base Plate (1) to the Isolation Plate (5).
 4. Characterized in that after ground shaking subsides, Tension Springs or Viscous Dampers (4) of claim 3 contract and revert the said Isolation Plate (5) of claim 1 back to the original position it held prior to ground shaking.
 5. Characterized in that after the ground shaking subsides, Tension Springs or Viscous Dampers (11) of claim 3 contract and revert the said Isolation Plate (5) of claim 1 rotationally back to the original position it held prior to ground shaking. 